The present invention relates to a satellite telecommunications facility capable of covering a plurality of distinct Earth coverage areas. In particular, it applies to the field of direct television broadcasting to a plurality of geographical coverage areas.
Known direct broadcast television satellites are provided to beam a determined number of channels to a determined Earth coverage area with satisfactory backup or redundancy.
For present television Standards, e.g. D2-MAC, one Travelling-Wave Tube (TWT) amplifier is provided per channel, the power of the amplifier currently lying in the medium range 50 watts to 130 watts.
Under these conditions, the system needs to be equipped with a certain number of replacement amplifiers used as redundancy in order to mitigate failure in any one of the power amplifiers.
From the point of view of users, it is not good enough merely to provide replacement (130-watt) amplifiers on board the satellite because the satellite may itself fail for a variety of reasons.
In order to provide almost perfect backup, it is currently necessary to provide two satellites capable of beaming the same channels to a coverage area. For example, if a satellite is to relay five D2-MAC television programs, it could itself include five TWT amplifiers (providing 130 watts per channel), and it could be associated with a backup other satellite which in turn includes another five (130-watt) TWT amplifiers.
Nowadays, it is almost essential when launching a direct broadcast television satellite for the a satellite to be capable of relaying High-Definition Television, for which marketing is currently under very active consideration, thus ensuring that the satellite is not only profitable now, but will remain so over the next few years.
The difficulty lies in the fact that future High-Definition Television requires the repeater satellite to have amplifiers providing much higher power than the amplifiers currently in use. For example, an HD-MAC Standard channel will require a high power 230-watt amplifier instead of the medium-power 130-watt amplifier which is currently sufficient for a D2-MAC Standard channel.
Current advice is to solve this problem by equipping satellites presently intended for D2-MAC channels with overdimensioned amplifiers capable of subsequently transmitting HD-MAC Standard channels.
Given the above numerical data, this means that for one coverage area, it is necessary to provide two satellites each including five 230-watt TWT amplifiers.
Therefore, given this currently-held concept, in order to cover two distinct areas, it is necessary in all to provide up to four overdimensioned satellites of this type. A drawback with this is that it requires very large investment to be made in a future market which is entirely hypothetical because it is not currently known if and when High-Definition Television will really be marketed.